1. Field of the Invention
The present invention relates to an electric motor having two coil bundles, and to an electric tool provided with such an electric motor. The present invention also relates to a method for producing the electric motor.
2. Description of Related Art
Electric Motors used for electric tools have been proposed for improving the cooling efficiency of electric motors. For example, a first coil bundle and a second coil bundle are set onto a first coil winding part and a second coil winding part of a stator core, respectively. Then, a gap is provided at roughly the center of the coil end of the first coil in a radial direction of the rotor. The gap extending in the circumferential direction of the rotor is formed by moving a part of the first coil toward the rotor. Such arrangement is disclosed in Japanese patent application publications No. 2001-292544. Thus, cooling efficiency of the motor can be improved.
However, with conventional electric motors, since movable distance of the part of the first coil toward the rotor is insufficient, only a tiny gap can be created. Accordingly, the air from the fan does not flow easily, so an improvement in cooling efficiency of the motor was not realized. Further, in order to enhance cooling efficiency, the coil end part of the bundle is preferably manually divided into two bundles having number of coil turns equal to each other in order to provide the gap between the divided two bundles. However, significant cost and production time have been required in order to count the number of coil turns and form the gap after setting the coil bundle.